Implementing AR construction navigation with iPhone RTK surveying: intuitive guidance even for solo work

Recently, a new technology called iPhone RTK surveying has begun to emerge in construction-site surveying. Tasks such as staking out and as-built management, which traditionally required skilled surveyors and expensive specialized equipment, can now be performed with high accuracy using just a smartphone. The key to this is the fusion of RTK (real-time kinematic) positioning technology using the iPhone and construction navigation that leverages AR (augmented reality).

In this article, we explain in detail—using concrete use cases—the mechanism and benefits of AR construction navigation made possible by introducing iPhone RTK surveying on-site. Let’s look at how this cutting-edge smartphone surveying solution, "allowing a single worker to intuitively guide work on-site," is changing the conventional norms of the construction industry.

Table of Contents

• What is iPhone RTK surveying technology

• What is AR construction navigation

• Specific on-site use cases - Pile-driving guidance: precise point indication with AR - As-built management: immediate verification with point cloud scans - AR display of buried utilities: visualizing subsurface infrastructure - Overlaying point cloud data: comparison with design models - One-person work support: contributing to labor savings

• Intuitive usability and labor-saving effects

• Summary

• FAQ

What is iPhone RTK surveying technology

• iPhone RTK surveying* refers to a technology that combines a smartphone (particularly an iPhone) with an RTK-GNSS receiver to achieve centimeter-level positioning accuracy (cm level accuracy, half-inch accuracy) comparable to traditional surveying instruments. RTK (Real-Time Kinematic) is a method that corrects satellite positioning errors to obtain high-precision coordinates in real time, dramatically improving GPS positioning, which normally has errors of several meters. iPhone RTK surveying brings RTK technology to the iPhone by attaching a small dedicated GNSS antenna and receiver to the iPhone and receiving correction information via communications (such as network-based RTK base station services or the CLAS signals from Japan’s Michibiki satellite service), allowing you to measure your position with approximately 1-2 cm (0.4-0.8 in) horizontal and 2-3 cm (0.8-1.2 in) vertical accuracy.

Receiver devices that attach to an iPhone (for example, a pocket-sized LRTK unit) weigh only around a hundred and some grams and are used by attaching to the back like a smartphone case or mounting on a dedicated pole. Because they can connect wirelessly via Bluetooth and the like, there is no hassle of cable connections. The iPhone itself is also being equipped with positioning chips that support multi-GNSS and dual-frequency, and in combination with a dedicated device it enables more stable, high-precision positioning. Power can be supplied from the smartphone or from an internal battery, so sufficient operating time for long outdoor use (e.g., about 8 hours) can be ensured.

In this way, by turning a smartphone itself into a high-precision surveying instrument, it has become possible to obtain accurate global coordinates on-site without special surveying equipment or specialized skills. Positioning results are displayed instantly in the smartphone app and can be used, as with conventional instruments, for tasks such as measuring control points and guiding to coordinates on design drawings. Furthermore, iPhones are equipped with high-performance cameras and LiDAR scanners, so combining this high-precision positional information with those sensors allows a single device to handle photogrammetry (photogrammetry) and point-cloud measurement via 3D scanning, which is a major advantage.

What AR Construction Navi Is

AR Construction Navi is a system that uses AR (augmented reality) technology to navigate work at construction sites. Specifically, when you view the site through a smartphone such as an iPhone, design drawings and construction instruction information are overlaid on the screen as virtual objects. For example, it intuitively guides workers by placing virtual guides in the real space—such as markers indicating "the position where a pile should be driven" or colored areas showing "the depth to be excavated."

Traditionally, setting out construction positions (layout marking) and confirming the locations of buried objects required numerical and visual assessments using drawings and surveying instruments, demanding specialized knowledge. AR construction navigation, when introduced, allows work to be done while directly viewing on a smartphone screen the state in which the site and drawing information are aligned, so even inexperienced personnel can determine accurate work positions without hesitation. It is precisely because of the centimeter-level accuracy (cm level accuracy (half-inch accuracy)) position information obtained by iPhone RTK surveying that the positions of AR-displayed guides also match the actual field without offset, enabling navigation that reflects reality.

This AR construction navigation is provided through a dedicated surveying and construction-support app. By loading construction drawings, BIM/CIM 3D models, or pre-configured coordinate data into the app, you can overlay them onto the actual site scenery through your smartphone screen. Even when you change your position or viewpoint, the iPhone’s position and orientation sensors, together with RTK positioning data, keep the virtual objects fixed in their correct locations, allowing you to grasp the completed form of the site and any points requiring attention on the spot, as if looking at a perspective drawing of the future.

Concrete on-site use cases

What can be achieved on real construction sites by combining the latest iPhone RTK surveying with AR construction navigation? Here, we present representative use cases and describe their benefits.

Stake Setting Guidance: Precise Point Indication with AR

In building and civil engineering stake-setting work, placing stakes at exact locations according to the design drawings is essential. Traditionally, a surveyor would use a total station to determine positions, and another person would hold the stake and be guided while working.

*Iphone RTK surveying* and AR construction navigation can guide you on the smartphone screen to pre-set stake positions. The worker holds an iPhone in one hand and looks over the site; by simply walking along the virtual markings displayed on the screen (for example, a flag standing on the ground or a target mark), they can arrive at the correct position. As they approach the target coordinates, distance and direction are displayed in real time, and once positioned within an error of a few centimeters (a few in), they simply drive the stake at that point. This series of stake-setting tasks can be completed by one person, eliminating the need to assign a surveying assistant as was previously required, so even on sites short of manpower accurate staking can be performed efficiently.

As-built management: immediate verification with point cloud scanning

As-built management for earthworks (checking post-construction shapes and dimensions) is another area where iPhone RTK surveying + AR proves highly effective. For example, when verifying the volume of fills or excavations, it previously took several days because the existing terrain had to be surveyed and the data processed in the office. By combining the iPhone's LiDAR scanner with RTK surveying, you can obtain high-precision 3D point cloud data simply by scanning the surroundings on site. Since each point is assigned accurate coordinates, you can immediately perform volume calculations and cross-section checks. Measurement results are shared with the office via the cloud, allowing real-time verification of as-built data from the office.

By being able to immediately ascertain the as-built condition on site, you can determine on the same day whether "the fill has reached the design quantity" and "the excavation has reached the specified depth," and if there is a shortage or excess you can immediately issue instructions for additional work or corrections. Traditionally there was a time lag from surveying to reporting that caused rework, but with this solution confirmation and correction are completed immediately after construction, greatly contributing to quality assurance and shortened schedules. Also, if you upload the design model data to the cloud, you can automatically overlay it with the point cloud acquired in the field and visually confirm via AR display whether the design geometry and the as-built match. This makes as-built management work faster and more reliable.

AR display of buried objects: visualizing underground infrastructure

AR construction navigation also plays an active role in understanding structures and pipes buried underground. If you prepare design drawings and buried-location data for the buried objects in advance, it is possible to display virtual pipes and cables in AR at their exact positions based on iPhone RTK surveying. By simply holding up a smartphone before excavation, you can "visualize" on the spot the routes of underground pipes and the locations of buried objects. Because workers can visually recognize invisible obstacles, the risk of accidentally damaging pipes can be greatly reduced, and it also helps in planning safe heavy-equipment work paths.

Also, when inspecting buried facilities in the future after completion, you can retrieve the original data and display it in AR to accurately determine the locations of structures lying beneath the pavement. Traditionally, you could only infer their positions from paper as-built drawings and survey stakes, but with AR construction navigation, anyone can intuitively share the precise locations of buried installations.

Overlaying point cloud data: comparison with design models

Point cloud data captured with an iPhone and LiDAR, and current 3D models created by photogrammetry, can also be easily overlaid and displayed with the design-stage BIM/CIM model. For example, if you scan the site before constructing a structure and place the planned 3D model onto that point cloud, you can verify before work begins whether the plan properly fits the actual site geometry. By using AR construction navigation, simply viewing the site through a tablet or smartphone screen lets you confirm how a virtual structure is perfectly overlaid on the real-world scene, making explanations to clients and stakeholders much easier. Because AR lets you share the finished appearance on the spot—something that paper drawings or two-dimensional photos have difficulty conveying—consensus building and adjustments to construction plans should proceed more smoothly.

Even during construction, by comparing the design model with point cloud data acquired periodically, you can continuously check whether the as-built condition is progressing according to the design. If discrepancies arise, they can be detected early and corrected, preventing rework. In this way, visual verification by overlaying point clouds and the model is effective not only for improving the accuracy of quality control but also as a communication tool for all stakeholders to share the current status.

Support for Single-Person Work: Contribution to **reduced manpower**

With the functions described above, iPhone RTK surveying and AR construction navigation make a major contribution to reduced manpower in surveying and construction management tasks. Surveying work that was traditionally carried out by two-person crews or teams can now be completed by a single person with nothing more than a smartphone and a simple device. Pile-driving work no longer requires an assistant, and in as-built management the site representative can handle everything from measurement to data sharing. Even for photo documentation and inspections, a single staff member with an iPhone can obtain high-precision geotagged data, so there is no need to call a specialist surveying team for each task.

The fact that this can be done by one person is extremely attractive to the construction industry, which suffers from chronic labor shortages. Even when a site must be run with a limited crew, smartphone surveying allows each person to quickly take measurements as needed and share them immediately, reducing waiting times and wasted personnel coordination. It is also effective from a safety standpoint: measurements in hazardous locations can be checked and instructed remotely using AR overlays, reducing the occasions when workers must enter danger zones. As a result, it can be said to be a technology that contributes to achieving both productivity and safety on site.

Intuitive Operation and Labor-Saving Effects

One of the biggest advantages the combination of iPhone RTK surveying and AR construction navigation brings to the field is its intuitive usability. Offered as smartphone apps, these functions can be used with the same feel as common map apps or games, so there’s no need to worry about the complex settings or measurement procedures typical of specialized equipment. You can record survey points simply by moving the phone according to on-screen instructions, or have positional coordinates automatically saved by pointing the camera at the target location—bringing a level of ease that anyone can use. AR’s visual guidance is clearer than words, allowing even non-experts to perform accurate work intuitively.

This ease of operation directly leads to reduced staffing (enabling work with smaller crews). Because on-site staff can use it without lengthy training, even newcomers and engineers from other fields can participate in surveying and measurement work, allowing for more effective use of personnel. If each person can collect the data they need with a smartphone per person, the site can operate self-sufficiently without relying on a dedicated surveying team. In addition, real-time data sharing and visualization dramatically accelerate decision-making and reduce wasted waiting time and duplicated work. From the field come voices such as, "Once you experience this convenience, you can’t go back to the old way," and iPhone RTK surveying and AR navigation are steadily transforming on-site work styles.

Summary

The introduction of *iPhone RTK surveying* and AR construction navigation is an innovative solution that powerfully promotes DX (digital transformation) on construction sites. The industry is shifting from traditional construction management that relied on expensive surveying equipment and large crews to an era in which each site worker can instantly perform surveying and verification with an iPhone in the palm of their hand. Centimeter-level positioning information (cm level accuracy (half-inch accuracy)) and intuitive AR-based guidance enable dramatic improvements in quality and productivity. Real-time sharing of survey data also smooths collaboration among stakeholders and, in turn, contributes to shorter project schedules and reduced costs.

Smartphone surveying technologies that are rewriting conventional on-site practices are expected to become increasingly widespread. The smartphone surveying techniques that leverage LRTK can be applied not only to advanced construction management but also to everyday simple surveying, and are helping to usher in an era in which anyone can easily perform surveys whenever needed. Please take advantage of this cutting-edge technology and apply it to next-generation on-site operations.

FAQ

Q1. Can surveying really be done using only an iPhone? A1. Yes. By combining a dedicated RTK-GNSS receiver with an app, iPhone RTK surveying is possible. By attaching a small positioning device to the iPhone (for example, an LRTK) and receiving correction information for high-precision positioning over a network, you can measure positions with cm level accuracy (half-inch accuracy) comparable to conventional surveying instruments. No special equipment is required; your hand-held smartphone can effectively become a high-precision surveying instrument.

Q2. What is RTK? A2. RTK (Real-Time Kinematic) is a technique that corrects satellite positioning (such as GPS) errors using base station data to obtain high-precision positions in real time. Ordinary GPS positioning has errors of several meters, but RTK can reduce errors to a few centimeters. In iPhone RTK surveying, this RTK correction information is received and used by the smartphone to improve accuracy.

Q3. Do you need any special qualifications or knowledge to use iPhone RTK surveying? A3. You can use it without a professional surveyor's qualification. The smartphone app is intuitive, and by following the on-screen instructions anyone can use it for surveying and AR navigation. However, basic surveying knowledge (the concept of reference points and the selection of measurement locations) and the ability to read and interpret construction drawings will make it easier to use. In any case, it is certainly easier to learn compared to traditional surveying instruments.

Q4. Which iPhone models is it available for? A4. In general, it is available on the latest iPhone and iPad models. The dedicated hardware is provided as a case-type attachment for iPhone and works without issue on iPhone 12 and later models. On iPhone 12 Pro/13 Pro/14 Pro and later models equipped with a LiDAR scanner, you can fully leverage the point-cloud scanning functionality. The app itself is for iOS/iPadOS, but some hardware is also compatible with Android devices and can be attached and used with magnetic mounts, etc.

Q5. Is the accuracy inferior compared to conventional surveying equipment? A5. The accuracy obtained with iPhone RTK surveying is at a level comparable to conventional GNSS surveying equipment. Under good conditions, horizontal accuracy of approximately ±1-2 cm (±0.4-0.8 in) and vertical accuracy of approximately ±3 cm (±1.2 in) can be expected, and there are verification results showing the difference was only a few millimeters (a few tenths of an inch) even when compared with high-end surveying instruments. However, accuracy degrades in urban areas with a lot of metal or in environments where satellites are difficult to acquire, the same as with ordinary GNSS devices. If appropriate correction information is received and calibration on known points is performed when necessary, survey accuracy sufficient for general civil engineering and building construction can be achieved.